Safety helmet



FIG. 1 is a front elevational view of the design for a safety helmet;

FIG. 2 is a rear elevational view of the design of FIG. 1;

FIG. 3 is a top plan view of the design of FIG. 1;

FIG. 4 is a bottom plan view of the design of FIG. 1;

FIG. 5 is a left side elevational view of the design of FIG. 1;

FIG. 6 is a right side elevational view of the design of FIG. 1; and,

FIG. 7 is a top, front, left side perspective view of the design of FIG. 1. 

The ornamental design for a safety helmet, as shown and described. 